The epidermal growth factor receptor (EGFR, Erb-B1) belongs to a family of proteins, involved in the proliferation of normal and malignant cells (Artega, C. L., J. Clin Oncol 19, 2001, 32-40). Overexpression of Epidermal Growth Factor Receptor (EGFR) is present in at least 70% of human cancers (Seymour, L. K., Curr Drug Targets 2, 2001, 117-133) such as, non-small cell lung carcinomas (NSCLC), breast cancers, gliomas, squamous cell carcinoma of the head and neck, and prostate cancer (Raymond et al., Drugs 60 Suppl 1, 2000, discussion 41-2; Salomon et al., Crit. Rev Oncol Hematol 19, 1995, 183-232; Voldborg et al., Ann Oncol 8, 1997, 1197-1206). The EGFR-TK is therefore widely recognized as an attractive target for the design and development of compounds that can specifically bind and inhibit the tyrosine kinase activity and its signal transduction pathway in cancer cells, and thus can serve as either diagnostic or therapeutic agents. For example, the EGFR tyrosine kinase (EGFR-TK) reversible inhibitor, TARCEVA®, was recently approved by the FDA for treatment of NSCLC and advanced pancreatic cancer. Other anti-EGFR targeted molecules have also been approved such as IRESSA®.

Despite the early success of Tarceva, it has become clear that selectively targeting individual kinases can lead to the development of drug resistant tumors. Cells that have developed mutations within the drug/kinase binding pocket display a growth advantage in the presence of drug eventually leading to disease progression. Current clinical strategies aimed at combining these molecularly targeted drugs with standard chemotherapeutics, radiation, or other targeted agents will lead to novel strategies to improve overall response rate and increase the number of complete remissions.
Furthermore, elucidation of the complex and multifactorial nature of various diseases that involve multiple pathogenic pathways and numerous molecular components suggests that multi-targeted therapies may be advantageous over mono-therapies. For example, the use of EGFR inhibitors in combination with histone deacetylases (HDAC) has been shown to produce synergistic effects. Histone acetylation is a reversible modification, with deacetylation being catalyzed by a family of enzymes termed HDAC's. HDACs are represented by X genes in humans and are divided into four distinct classes (J Mol Biol, 2004, 338:1, 17-31). In mammalians class I HDAC's (HDAC1-3, and HDAC8) are related to yeast RPD3 HDAC, class 2 (HDAC4-7, HDAC9 and HDAC10) related to yeast HDA1, class 4 (HDAC11), and class 3 (a distinct class encompassing the sirtuins which are related to yeast Sir2).
Recent advances suggest that EGFR-TK inhibitors in combination with HDAC inhibitors may provide advantageous results in the treatment of cancer. U.S. Provisional Application No. 60/843,644, filed on Sep. 11, 2006, U.S. Provisional Application No. 60/895,873, filed on Mar. 20, 2007, U.S. Ser. No. 11/852,604, filed Sep. 10, 2007, and U.S. Ser. No. 11/852,585 filed on Sep. 10, 2007, the contents of which are hereby incorporated by reference, describe quinazoline containing zinc-binding moiety based derivatives that have enhanced and unexpected properties as inhibitors of epidermal growth factor receptor tyrosine kinase (EGFR-TK), HDAC and HER2. It was surprisingly found that the compounds have enhanced activity when compared to the activities of separate molecules individually having the EGFR-TK and HDAC activities and combinations thereof. In other words, the combination of pharmacophores into a single molecule may provide a synergistic effect as compared to the individual pharmacophores.
The quinazoline compounds described above have been demonstrated as effective in decreasing tumor size in various animal models. It would be advantageous to prepare pharmaceutically acceptable salts of these quinazoline compounds.